Treatment of peat.



N. TEsTRuP & T. RIGBY.

TREATMENT 0F PEAT APPLICATION FILED FEB. 25. I9I3.

Patented Nov. 16, 1915. 2 SHEETSAHEET l.'

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TREATMENT 0F FEAT.

APPLlcAnoN FILED FEB. 25. 1913.

LTGOAS. Patented Nov. 16, 1915.

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NILS TESTRUP, OF LONDON, ENGLAND, AND THOMAS R'IvGBY, OF DUMFRIES,SCOTLANI), ASSIGNORS T0 WETCARBONIZING LIMITED, OF LONDON, ENGLAND.

'TREATMENT OF FEAT.

Application filed February 25, 1913.

To all whom it may conce/rn.' 1 Be it known that we, Nuls Tns'rnur, asubject of the King of Great Britain and Ireland, and residing at 3 DeanFarrar street, London, S. W., England, and THoMAs Rioni', a subject ofthe King of Great Britain and Ireland, and residing at (il LoreburnAstreet, Dumfries, Scotland, have invented certain new and usefulImprovements inthe Treatment of lleat,-of which the following is aspecification.

This .invention relates to the treatment of peat by such process of wettreatment o f peat as apparently by chemical decomposition of somecomponent of the peat renders its water more freely removable, forexample the wet ca rbonizing of the same.

In wet carbonizing peat in apparatus such as has been proposed byEkenberg (British Letters Patent No. 10834 of 1903) wherein rotatingtubular elements are employed., the provision ofthe rotating elements ishable to be a source of substantial cost in operation, owing to wear andthe need or replacement of the parts, and moreover, is a large factor inthe initial cost of the apparatus.

We have observed that if, instead of providing rotating scrapers andother devices within the tubular and other elements, the peat pulp to becarbonized is forced through the apparatus at considerable velocity, itis possible by this means alone to prevent blocking and otherdifficulties which the rotation of the elements was intended to avoid,and that it becomes unnecessary therefore to provide such rotatingelements. 1We have discovered, however, that the high rate of flow tendsto result in incomplete carbonization due as it would appear from ourexperiments to the rate at which the carbonizing reaction proceedshaving a limited velocity. The material requires therefore to bemaintained for some appreciable period at the carbonizing temperaturebefore 'it is allowed to cool by transfer of its heat to a freshquantity of the material. It must be borne in mind, however, that suchtime element in the reaction 1s, as our experiments suggest, dependentupon the temperature Specication of Letters Patent. v

Patented Nov.. 16, i915.

seria1No.75o,561. l

sired degree can be gaged by the readiness withwhich the macerated pulpfrom the carbonizers parts from its water in a filter press or the liketo give a coherent cake of relatively low water content andunaccompanied by objectionable shining up of the cloths. In operatingtherefore with a high rate of flow of the peat pulp as above indicated,We make allowance for the above features.

The present invention consists in a method of eifecting wetcarbonization of peat in which the peat is caused to flow at such avelocity through the apparatus that moving scraping or otherdevices'become unneces- Isary, and in which the peat, after having beenraised to the desired carbonizing temperature or thereabout, ismaintained at this temperature for a sutlicient period to allow thecarbonization to complete itself to the desired extent.

In carrying the invention into effect, we generally arrange that the rawpeat shall be gradually heated regeneratively before external heat isapplied finally to raise the temperature of the material to that atwhich it is to be maintained while carbonizing is being completed.

The accompanying drawingl shows diagrammatically in Figure l one form ofa complete carbonizing element adapted for such. regenerative heatingand a vessel for retaining the heated peat; Fig. 2 shows a preferredform of bafiie; and Fig. 3 shows a modilied form of apparatus suitablefor carrying the invention into effect. v

The carbonizing element is composed of long concentric stationary tubes,say respecn tively of 3g; inches internal, -t inches external and 5inches internal diameter and for instance between. 700 and 1,000 feet intotal length, and which may be as shown divided into ive sections orsets of tubes. Through the outer tubes, t and o, ofthe first two sets'of tubes .a hot liquid, such as the efiluent from thelter presses ofthe installation is introduced at c, and passes through the tube, a,bend, Z and tube b, in the direction indicated by the arrows, andthereafter passes to the outlet, c for example to any suitable wastesuch as the moss. The raw peat to be carbonized enters the carbonizingelement by the inner tube, and flowing in a direction opposite to thatof the hot effluent or other liquid receives heat from the latter and isthereby regeneratively heated. @Il

fluent entering the surrounding jacket atc. The partially heated peat isnow conducted" 'by a bend, 2', to the inner tube, j, in which it isfurther regeneratively heated, but in this `case by the peat which hasbeen wet carbonized and is flowing in the opposite direction in theouter tube, As the raw peat in thus owing through the tube, j, issurrounded by wet carbonized peat the temperature of which increaseswith decrease in the distance from the source of the wet c'arbonizedpeat, it becomes necessary" to prevent radiation of heat from the hotpeat. rlhis is avoided byarranging that the colder' material, afterpassing through the tube, j, is conducted by way of a bend m, into theouter tube, n, of the next tube set, the inner one, 0, of which containsthe hot wet carbonized peat and conveys the saine by way of a bend, p,to the outer tube, c. lnthis way the colder material passing in theouter tube, fm, forms to some extent a lagging which diminishes loss ofheat.

The raw material on leaving the tube, n, then passesinto an inner tube,Q, and having passed to the end thereof its direction of flow isreversed, and it passes through the outer' concentric tube, r.' In thistube set vthe external heat necessary finally to raise the temperatureof the material to that which has been selected for the maximum issupplied, this being effected in the arrangement shownl by means of asteam jacket, s, to which steam at a pressure of about 190 lbs. persquare inch is supplied, such steam being obtained, for example, from ahigh 'pressure exhaust of a high pressure steam engine supplying powerfor the installation, and after leaving the jacket and being' otherwiseutilized is returned to the steam generating plant as feed water. Bythus arranging that the colder material entering this part of thecarbonizer is confined to the.

inner tube, rj, the advantage is obtained that the jacket wall is indirect contact with the material which is to be heated to the highesttemperature. The material having now been raised to the requiredtempera-` tui'e leaves the tube, r, and passes by wayv of a conduit, t,into a closed vessel, u, which is provided with a rotating mixer, fu,and intermediate baffles, tu. The rate of flow of the material is bythis means materially reduced, so that it remains for instance abouttwenty minutes although this may be substantially greater or less asindicated above in. the vessel, u, before. passing into the conduit, a4,by which it is conveyed to the inner tube, 0, of the regenerative partof the carlicnizing element.

lt will be understood that where in carry- 4peat may be supplied to thatregenerative partvof several carbonizing elements from the same conduit,such regenerative parts in some cases being grouped together apart fromthe rest of the carbonizing elements. A mixing lvessel may beprovidedfor each carbonizing element, or if preferred, several suchelements may deliver the hot peat into the saine-vessel or, according toanother arrangement, the mixing vessels may deliver the carbonized peatinto the same conduit from which it is distributed to the carbonizingelement-s for the purpose of effecting regenerative heating of theincoming raw material. Those regenerative portions pertaining to severalcarbonizers and in which hot peat pulp supplies heat may likewise begrouped together and the externally heated portions grouped in one ormore steam jackets.

A rate of flow which we have found satisfactory for running theapparatus with stationary tubes was with a particular sample of peatpulp finely macerated and containing' about 94 per cent., water 9H persecond to as much as 3 ft. per second or higher. We find the heattransmission per unit surface from peat to peat, and from steam to peatincreases rapidly with an increase of velocity, and when working with avelocity of flow of about 211- ft. per second, a steam jacket of about100 ft. in length is suitable.

The length of the tube element in which the regeneration goes on varieswith the velocity and the amount of heat' which has to be transmitted orregenerated, and the diti'erence in the ten'iperature between the heattransmission surfaces. We find for instance that the length of tubeelement required when working with a velocity of ft. per second is about950 ft. in the regenerative portion, and in addition to the length ofthe steam jacket, this being with a difference of temperature on theregenerative heating surface of about 40 C. It is obvious that 'thelength of tube can be varied to suit the sible by this means alone toprevent blocking v u and other difheulties which the rotation of l theelements in former apparatus (see Britislrlatent specifications Nos.10834 of 1903, 6041 of -1910 and 17610 of 1911) wasv intendedl to avoid.lVe havefurther observed, however, that with such. rate of flow incensethere is a tendency for incomplete carboni- Zation and that as it wouldappear from our experiments, the rate at which the carbonizing reactionproceeds has a definite velocity, the material requires therefore to bemaintained for some appreciable period at the carbonizing temperaturebefore it is allowed to cool by transfer of its heat to rauT materialentering the carbonizer. c

rl`he pressure which may be required in the case of an apparatus of thedimensions which have been instanced to .give the pulp the desiredvelocity through the apparatus has been observed by us with oneparticular peat finely macerated and containing say 93.5% of water to,amount to several hundreds of 4pounds per square inch-800 lbs. inonepary effected in a vessel of a special character separate entirely fromthe concentric tubular system, it Will be understood this is referred toby Way of example only and that the result may be obtained as shown inFig. 3 by causing the peat to flow through a section of tube u of therequisite length in which it is merely prevented from losing its heat bysuitable lagging means w.

lt is important in order to secure efficient heat regeneration, rapidheat transmission and general economy in the Working of the apparatus toinsure a substantial agitation Within the peat pulp flowing through theapparatus, and While the rapid flow alone produces apparently themovement necessary to prevent lodgment on the walls our experimentssuggest a tendency to channeling or stratification in the pulp. For'thisreason among others We prefer to provide specific devices such asperforated ballesfc. g. as shown to an enlarged scale in Fig. 2, adiaphragm y with a large central orifice, in the path of the flow and atsuitable distances apart these acting to produce a churning or eddyingin the material. In order to prevent likelihood of deposition in theangles formed by these devices it is desirable to provide conedapproaches thereto as shown. Again if cross connections be provided atintervals which interchange the streamsl of peat from annulus to coreand vice versa,

each interchange will secure an agitation of ence to the drawing is thatitenables a construction to be obtained in which as with thatillustrated the raw peat passes to the maximum extent through the innertubes of the system this leading to. a reduction. of

pressure required for propulsion owing to the raw peat with therelatively high viscosity or shear on the tube Walls passing throughthat part Where the proportion of surface of Wall to cross sectionalarea is least,

The apparatus may be constructed with any desired number of concentrictubes and layers of peat flowing therein. Thus the regenerator portionmay be formed of four concentric tubes in alternate ones 'of which flowrespectively peat to and peat from the carbonizer portion proper.

Having` now described our invention What We claim as new and desire tosecure by Letters Patent is :FM

l. Process for the heat treatment of peat which consists in causing thepeat to tra-vel through heating elements at such a rate that .depositionof the peat in said elements is prevented by virtue of the rapid rate offlow of the peat itself.

2. Process for the heat treatment of peat which consists in causing thepeat to travel through heating elements at such a rate that depositionof the peat in said elements is prevented by virtue of the rapid rate offlow of the peat itself, and in which the peat is maintained at or aboutthe desired maximum temperature until the requisite degree of treatmenthas been attained.'

3. A method of Wet carbonizing peat, in which the peat is heated to apredetermined temperature under pressure, maintained at about thistemperature for a relatively eX- tended period and then caused to flowthrough fixed tubes in which it is churned at high speed at intervals bymixing devices.

el. A process for the heat treatment of peat consisting in causing thepeat to flow through heat interchanging passages that by reason of therate of flow alone deposition of the peat in said Ypassages is preventedand in disturbing said liow at intervals by baffling.

In testimony whereof we have signed our naines to this specification inthe presence of two subscribing witnesses.

NILS TESTRUP. THOMAS RIGBY. `Witnesses to the signature of Nils TestrupBnR'rnAM H. MATTHEWS, E. C. WALKER. lVitnesses to the signature of T.Rigby:

Bnn'rnxar H. Ma'rrnnws, JAMES HENDERSON.

It is hereby certied that in Letters Patent No. 1,160,463, grantedNovember 16,

1915, upon the application of Nils Testrup, of London, England, andThomas Rigby, of Dumfries, Scotland, for an improtfement in Treatment ofPeat, an-v ez'Tor eppeais in the printed specoation reqnirng correetionas follows: Page 2,

line 111-2, for the' .Word of read in; and `that the .seid Letters'Patent should be reed with this correction therein that the seme mayconform to the record c*e the cese in the Patent Office.

y Signed and seeledths 24th dey of October, A. D., 1916.

F. W. H. CLAY,

[with] Acting Commissioner of Paten/s.

